A series of Co1-xNixB alloy catalysts were synthesized in ethanol by chemical reduction in an ice-water bath. The catalytic hydrolysis of an alkaline NaBH4 solution was studied by changing the Ni content in the Co1-xNixB catalyst. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy revealed that the as-prepared Co1-xNixB alloys were ultrafine nanoparticles in amorphous form. Hydrogen generation measurements showed that the as-prepared Co1-xNixB alloys exhibited excellent catalytic activity. The hydrogen generation rate firstly increased as the Ni content increased in the Co1-xNixB catalyst, and it reached the highest at x=0.15, then decreased as x increased. The highest hydrogen generation rate at 298 K was 4228 mL·min-1·g-1 for Co0.85Ni0.15B during the catalytic hydrolysis of the alkaline sodium borohydride solution. The activation energies of the Co0.85Ni0.15B alloy and CoB were 31.87 and 34.25 kJ·mol-1, respectively. This showed that the Co1-xNixB alloys synthesized in ethanol had high activity.